Attachment plug and receptacle



July 7, 1931. 0. El MASON ATTACHMENT PLUG AND RECEPTACLE 2 Sheets-Sheet 1 Filed Nov. 14, 1928 July 7, 1931. c. E. MASON ATTACHMENT PLUG AND RECEPTACLE Filed Nov. 14, 1928 2 Sheets-Sheet 2 3 2 Ll k Patented July 7, 1931 UNITED STATES PATENT OFFICE CHARLES E. MASON, 0F UPPER DARBY TOWNSHIP, DELAWARE COUNTY, PENNSYL- VANIA, ASSIGNOR TO NOVELTY ELECTRIC COMPANY, OF PHILADELPHIA, PENN- SYLVANIA, A CORPORATION OF PENNSYLVANIA ATTACHMENT PLUG AND RECEPTACLE Application filed November 14, 1928. Serial No. 319,198.

My invention is designed to provide an improved attachment plug and receptacle affording means for directly grounding the casing of a tool or other device using electric current and the conduit system through which the current is supplied. In the preferred embodiment of my invention, the attachment plug is provided with a metallic conducting shell or case which is grounded upon the common ground of a multiple wire system preferably but not necessarily containing fuses in the live lines and housed within the shell. The casing of the receptacle complementary to the plug is likewise grounded upon the ground line of the multiple wire system.

My improvements are particularly applicable where heavy duty service is required, as, for instance, in connection with drills or hammers. The separate wires of the cables of such instruments are readily attachable to and detachable from binding posts electrically connected with contact prongs, and the cable covering is firmly gripped to prevent strain upon the connections of the wires with the binding posts. Preferably the connections between the binding posts and contact prongs are through detachable fuses, but if desired the fuses may be omitted and the binding posts and contact prongs made integral or connected through'unfused conductors. The contact prong of the ground line is preferably made slightly longer than the contact prongs of the live lines to insure grounding before the line circuits are completed.

The characteristic features and advantages of my improvements will more fully appear from the following description and the accompanying drawings illustrating the preferred embodiment of my invention.

In the drawings, Fig. 1 is a side elevation of a plug embodying my improvements: Fig. 2 is a longitudinal sectional view of the plug in position on a face plate; Fig. 3 shows detached parts of the plug and face plate in perspective; Fig. 4 is an end view of the plug; Fig. 5 is an end View of the outer end of the block shown at the left of Fig. 3 with its attached parts; Fig. 6 is an end view of the inner end of the same block; Fig. 7 is an end View of the outer end of the intermediate block shown in Fig. 3 with its attached parts; Fig. 8 is an end view of the inner end of the same block; Fig. 9 is a face view of the receptacle with conducting pins shown therein in section; Fig. 10 is a plan view of the receptacle block; and Fig. 11 is an end View of the receptacle block.

In the embodiment of my invention illustrated in the drawings, a hollow metallic shell 1 has an apertured end 2 from which projects a jaw 3 having a curved surface. A complementary clamping jaw 4 is connected with the jaw 3 by suitable screws 5, whereby the jaws may be drawn together to tightly grip a multi-wire cable 6 of a tool or other current consuming device (not shown).

The inner surface of the shell is provided with a T-shaped feather or bead 7 for positioning a slotted insulating block 8 in which is fixed a conducting ground post G. A screw 9 passes through an aperture in the shell 1 and block 8 into the post G for electrically connecting the shell to ground.

The member G has a projecting section G of semi-circular cross section to the fiat face of which a flanged clip 10 is clamped by a screw 11 to secure the ground wire 6a of the cable to the ground post. The opposite end of the post is recessed and split to form a spring socket 12.

A plurality of live line posts 13 are seated in the block 8; each post having a semi-circular section 14 projecting from the block and having a flanged clip 15 clamped thereto by a screw 16 for the attachment of the respective live cable Wires 6?). The opposite ends of the posts 13 are recessed and split to form resilient sockets 18.

A second non-conducting block 19 has a pin 20 seated therein and projecting from both ends thereof; one end of the pin being adapted for frictional engagement in the resilient socket 12. A plurality of posts 21 are seated in the block 19 and have pins 22 projecting therefrom beyond the block. The opposite ends of the posts are recessed and split to form resilient sockets 23.

Standard cartridge fuses 24 are inserted between the blocks 8 and 19 with their ends securely seated in the respective sockets 18 and 23. The blocks 8 and 19 are fixed together in spaced relation by a screw 24 and form, with the casing 1, a chamber 25 which is vented through a hole 26. in the block 19.

The plug is complementary to a non-co r ducting faceplate 28 having thereon a projecting boss 29 which fits in'the end of the shell 1 and contains apertures 30- for the passage of the pins 20 and 22.

The faceplate 28 has fixed thereto by screws 31 an insulating block 32 in'which are mountedconducting posts 33, 33 forming spring sockets 34, 34. seated in counterbores 35 concentric with the apertures 30 in the boss for receiving the ends of the pins 20- and '22 respectively. The posts 33, 33 have therein suitable terminal screws 36 for the, attachment of appropriate circuit wires.

The block 32 has screwed thereto metal clips or brackets 37 for attachment to a usual metallic wall box or receptacle forming a part of the conduit system' through which electricity is supplied. One of the clips 37 is connected by a screw 39 with the post 33 so as to ground the wall box thereon.

It will be understood that the pill. may be readily assembled and connected y inserting cartridge fuses in the sockets 18 and 23' and inserting the pin 20 in the socket. 120 The blocks are connected in spaced relation by the screw 24, and the cable 6, is passed through the apertured end 2 0f; the shell so that its wires 6a may be connected with the post G and its wires 6?) may be connected with the posts 13. The assembly may then be positioned in the shell 1; the relative longitudinal movement of the parts beinglimited by the engagement of the end of the block 8 with the cross head of the T-member 7 and the circumferential positioning of the parts being effected by the engagement of the stem of the T-member in the longitudinal groove in the block 8. The insertion of the screw 9 prevents separation or relative movement of the shell and the inserted members and grounds theshell on the post G and therepush or pull; accuracy of positioning being I assured by making the pin 20 and socket 34 of different diameter from the pins 22 and sockets 34:.

The enclosure of the conducting parts within a metal shell minimizes the fire hazard without increasing the electrical hazard since the plug shell and receptacle shell are grounded. The grounding of the shell is positive since the plug cannot be permanently assembled without the insertion of the grounding screw. The parts are readily separable to replace a blown fuse, and the blowing of a fuse does no damage since the bodies ofthe fuses are housed in a chamber from which pressure readily escapes through the vent hole 26..

Having described my invention, I claim:

' 1., A plug comprising a shell containing an insulating block, said block containing a ground post and live wire posts, means con-: meeting said shell and ground post, each of said posts having on one end wire clamping meansand the other ends of said posts: containing sockets, fuses housed in sockets; afore-- said, a second insulating block spaced rrom said first block and containing conductors, one ofsaid last named conductors being engaged in a socket aforesaid and the other of the conductorsin the second named block-eontaining sockets receiving said fuses, means connecting said blocks in spaced relation, said blocks and shell formingan expansion chamber for said fuses, and pins projecting from condutors in said second named block and housed within said shell.

2'. A plug comprising a shell membercontaining an insulating block member, one of said members containing a slot receiving a feather on theother, said block containing a ground post and live wire posts, means connecting said shell and ground post, each'of said posts having on one end wire clamping means and the other ends of said posts containing sockets, fuses housed in sockets aforesaid, a second insulating blookspaoed from said first block and containing conductors, one of said last named conductors being en'- gaged in a soeketvaforesaid, and the other of the conductors. in the second named block containing sockets receiving said fuses, means connecting said blocks; in spaced relation and pins projectin from conductors in said second named bloc and housed within said shell.

In witness whereof I have hereunto. setmy name this second day of November, 19.28.

i CHARLES E. MASON. 

